The transportation of intermodal containers on railcars has been a common practice for several decades. The sizes and capacities of the containers have steadily increased in time. Intermodal cargo containers have been standardized in various lengths such as 20, 24, 40, 45, 48 and 53 feet. Intermodal cargo containers have also been standardized in various widths. Typically, available cargo containers are either 96-inch (8'0") or 102-inch (8'6") in width. Today, intermodal containers are commonly available in the following dimensions: 20'L.times.8'6"H.times.8'0"W; 40'L.times.8'6"H.times.8'0"W; 45'L.times.9'6"H.times.8'6"W; and 53'L.times.9'6"H.times.8'6"W.
Each standardized cargo container has a different total load capacity. For example, the total load capacity of a typical 20-foot cargo container is approximately 52,900 pounds, while the total load capacity of a typical 40-foot or 48-foot cargo container is approximately 67,200 pounds.
The prior art has provided a variety of railroad freight cars adapted to carry intermodal cargo containers. Typically, such railcars are capable of carrying various configurations of different sized intermodal cargo containers. At times, a stacked arrangement of such cargo containers is employed.
One type of container car in use is referred to as a well car, since it has a container-receiving well between the wheeled trucks which support each end of the well car. The body of the car is generally at a low height, with containers in the bottom tier of a double-stacked container arrangement being supported approximately 10 inches above rail in a loaded car. Examples of such well cars are provided in U.S. Pat. No. 5,465,670, issued to Butcher on Nov. 14, 1995 and assigned to the present Applicant. Yet another railcar well design is disclosed in co-pending Canadian Patent Application Serial No. 2,175,440, filed in the names of Forbes and Coslovi on Apr. 30, 1996 and also assigned to the present Applicant. In order to transport as many combinations of standardized intermodal cargo containers as possible, the well of a typical well car is generally dimensioned to receive the longest and widest cargo containers commercially available.
During transport of intermodal cargo containers by rail, lateral and longitudinal forces act upon the cargo containers. These forces may be generated during switching operations and other car or train handling procedures. Typically, cargo containers are not latched to the car structure. Such containers simply sit on container support castings, which have guide blocks and locating cones welded to their flat top surfaces. A typical container support casting is illustrated in U.S. Pat. No. 5,501,556, issued to Butcher et al. on Mar. 26, 1996 and assigned to the present Applicant. The locating cones are each adapted to be received in a corresponding opening of a corner casting or a corresponding structural member of a container. The guide block serves to guide a container longitudinally during loading of the container into the well and onto the corresponding locating cone on the container support casting. Container support castings are conventionally located at the 40-foot corner locations of the well car floor. The practice to-date in this art is to have a plain support surface centrally within the railcar well, that is, a support surface which forms part of the well car floor and which is not provided with container support castings. Generally, cargo containers placed onto the floor structure of a well car are only restrained from longitudinal shifting by the container support castings.
When a second row of cargo containers is stacked onto a first row of containers in the well of a rail car, (i.e. when containers are "double stacked") the top row of containers is secured to the bottom row of containers with connecting devices known to those in this art as inter-box connectors. These connectors join the upper four corners of the bottom row of containers to the lower four comers of the top row of containers and positively lock the containers in three directions. The lateral and longitudinal forces which act upon cargo containers during their transport results in the displacement or shifting of a container from an initial location in the container well to some other position due to the inertial or dynamic forces acting on the containers during transit. Where a container is loaded into an empty well car and the length of well portion of the well car exceeds the length of the container placed therein, longitudinal shifting of that container within the well can be expected. When a long container is stacked over two 20-foot containers, container pitching from longitudinal impacts to the well car is not an issue because the long container on top stabilizes the two lower containers. The lower 20-foot containers in such a configuration cannot readily pitch and lift off the trailing container support castings in a frontal collision of the railcar. However, the situation is quite different with double-stacked 20-foot containers. The high center of gravity of the containers, combined with their shorter 20-foot length, means that container pitching will be more prevalent in a double-stacked configuration and that the trailing ends of the containers may lift several inches off the container support castings in a frontal collision of the railcar. This increases the possibility that the trailing containers will therefore lift off the cones and slide forward, thereby impacting the lead containers. Similarly, pitching of the lead containers at the lead ends thereof will occur in rear collisions of the railcar.
To resolve the problems discussed above, a number of manually operable container stops have been disclosed which are located centrally within the railcar well and which are intended to prevent the longitudinal displacement or shifting of 20-foot containers in the well of the car. One such manually operable container stop is disclosed in U.S. Pat. No. 5,465,670, issued on Nov. 14, 1995 in the name of Butcher and assigned to the present Applicant. Another pivotable container stop is disclosed in Canadian co-pending application Serial No. 2,175,445 filed on Apr. 30, 1996 in the names of Butcher and Coslovi, which application has been assigned to the present Applicant. In these known container stops, an operator must manually activate the stop by unlocking a mechanism in the railcar sidewall to allow the stop to pivot into the well of the car. When so disposed, the stop prevents the longitudinal displacement or shifting of 20-foot containers within the well. If it is desired to employ the well of the railcar for a 40-foot container, the prior art manually operable stops must be retracted by an operator by pivotally moving the stop out of the well portion of the railcar and into its retracted position within the railcar sidewall. Otherwise, the known container stops would interfere with the loading of 40-foot or 48-foot containers.
In contrast to the known container stop devices, the present invention seeks to provide a container stop which is automatically activated to prevent the longitudinal shifting of containers in a well of a well car when containers of a certain predetermined length are loaded into the well. The container stop according to the present invention automatically retracts from the well floor structure when full-length containers, such as 40-foot to 53-foot containers are seated in the well. The automatically activated container stop preferably acts in conjunction with a container guide in the railcar sidewall which provides a protruding deflector to longitudinally deflect shorter containers, such as those having a 20-foot length, as they are lowered into the well, so that such containers are seated within the well of the railcar in such manner as not to each interfere with the operation of the retractable container stop.